Transition probabilities and measurement statistics of postselected ensembles

It is well-known that a quantum measurement can enhance the transition probability between two quantum states. Such a measurement operates after preparation of the initial state and before postselecting for the final state. Here we analyze this kind of scenario in detail and determine which probability distributions on a finite number of outcomes can occur for an intermediate measurement with postselection, for given values of the following two quantities: (i) the transition probability without measurement, (ii) the transition probability with measurement. This is done for both the cases of projective measurements and of generalized measurements. Among other constraints, this quantifies a trade-off between high randomness in a projective measurement and high measurement-modified transition probability. An intermediate projective measurement can enhance a transition probability such that the failure probability decreases by a factor of up to 2, but not by more.Comment: 23 pages, 5 figures, minor updat

Learning Manipulation under Physics Constraints with Visual Perception

Understanding physical phenomena is a key competence that enables humans and animals to act and interact under uncertain perception in previously unseen environments containing novel objects and their configurations. In this work, we consider the problem of autonomous block stacking and explore solutions to learning manipulation under physics constraints with visual perception inherent to the task. Inspired by the intuitive physics in humans, we first present an end-to-end learning-based approach to predict stability directly from appearance, contrasting a more traditional model-based approach with explicit 3D representations and physical simulation. We study the model's behavior together with an accompanied human subject test. It is then integrated into a real-world robotic system to guide the placement of a single wood block into the scene without collapsing existing tower structure. To further automate the process of consecutive blocks stacking, we present an alternative approach where the model learns the physics constraint through the interaction with the environment, bypassing the dedicated physics learning as in the former part of this work. In particular, we are interested in the type of tasks that require the agent to reach a given goal state that may be different for every new trial. Thereby we propose a deep reinforcement learning framework that learns policies for stacking tasks which are parametrized by a target structure

Method of fabricating a photovoltaic module of a substantially transparent construction

A method characterized by the steps of positioning a plurality of uniformly dimensioned photovoltaic cells in registered relation with a plurality of openings formed in a planar tool is disclosed. The method allows acess to the P contact surface of each of the cells. The steps of the method are: (1) connecting the N contact surface of alternate cells to the P contact surface of the cells interposed therebetween, (2) removing therefrom residue of solder flux, (3) applying to the N contact surfaces of the cells a transparent adhesive, (4) placing a common transparent cover plate in engaged relation with the adhesive, (5) placing a film over the circular openings for hermetically sealing the openings, and (6) establishing a vacuum between the film and the cover plate

The evolution of the number density of compact galaxies

We compare the number density of compact (small size) massive galaxies at low and high redshift using our Padova Millennium Galaxy and Group Catalogue (PM2GC) at z=0.03-0.11 and the CANDELS results from Barro et al. (2013) at z=1-2. The number density of local compact galaxies with luminosity weighted (LW) ages compatible with being already passive at high redshift is compared with the density of compact passive galaxies observed at high-z. Our results place an upper limit of a factor ~2 to the evolution of the number density and are inconsistent with a significant size evolution for most of the compact galaxies observed at high-z. The evolution may be instead significant (up to a factor 5) for the most extreme, ultracompact galaxies. Considering all compact galaxies, regardless of LW age and star formation activity, a minority of local compact galaxies (<=1/3) might have formed at z<1. Finally, we show that the secular decrease of the galaxy stellar mass due to simple stellar evolution may in some cases be a non-negligible factor in the context of the evolution of the mass-size relation, and we caution that passive evolution in mass should be taken into account when comparing samples at different redshifts.Comment: ApJ in pres

Reproduction, early development, and larval rearing strategies for two sponge-dwelling neon gobies, Elacatinus lori and E.colini

A major goal of the aquaculture industry is to reduce collection pressure on wild populations by developing captive breeding techniques for marine ornamental species, particularly coral reef fishes. The objective of this study was to develop a rearing protocol for two recently described species of neon gobies that are endemic to the Mesoamerican Barrier Reef: 1) Elacatinus lori; and 2) Elacatinus colini. First, the current study describes the reproductive behavior and larval development of both species. Second, it evaluates the effects of different rotifer and Artemia densities on the survival and growth of E. lori and E. colini larvae. Third, it compares the survival and growth of E. colini larvae fed wild plankton to those fed a combination of rotifers and Artemia. Once acclimated, pairs of E. lori began spawning in 53.2 ± 12.4 d (mean ± sd), while pairs of E. colini took only 12.2 ± 10.3 d. E. lori produced more embryos per clutch (1009 ± 477) than E. colini (168 ± 83). E. lori larvae hatched 8.18 ± 0.4 days after initial observation with a notochord length of 3.67 ± 0.2 mm. In comparison, E. colini larvae hatched 6.8 ± 0.4 days after initial observation with a notochord length of 3.51 ± 2.3 mm. Both species settled as early as 28 days post hatch at 9–9.5 mm standard length, following the fusion of the pelvic fins to form a pelvic disc. During rotifer density trials, from 0 to 6 days post hatch, there was no significant difference in survival or standard length between treatments fed 10, 15 or 20 rotifers ml^− 1 for either species. During Artemia density trials, from 6 to 14 days post hatch, control treatments fed solely on 15 rotifers ml^− 1 had significantly higher survival than treatments that were fed rotifers in combination with 3, 6 or 9 Artemia ml^− 1. Finally, E. colini larvae that were fed wild plankton had significantly higher survival and growth than those fed with a combination of 15 rotifers ml^− 1 and 3 Artemia ml^− 1. The results of this study suggest that Artemia nauplii are not a suitable prey for E. lori or E. colini larvae. Our results demonstrate the feasibility of rearing E. lori and E. colini to settlement, and suggest that 10–20 rotifers ml^− 1 and wild plankton provide a viable starting point for optimizing the survival and growth of Elacatinus spp. larvae.We would like to thank the Belizean government and Fisheries Department for permission to conduct this research. Thank you to the staff at the International Zoological Expeditions for their support in the field. Special thanks to Katrina Catalano, Kevin David, Robin Francis, Jeremiah Seymour, James Ferrito, Derek Scolaro and Alex Ascher for their assistance in the lab and rearing larvae. Dr. John Crawford, Dr. Karen Warkentin and Dr. Jacqueline Webb provided helpful comments on this manuscript. This research comprises a portion of JEM's doctoral thesis requirements (Boston University). Funding was provided by a start-up award to PMB from the Trustees of Boston University, the IDC account of JA and a Warren McLeod Summer Research Scholarship awarded by the Boston University Marine Department to JEM. Additional funding was provided by two NSF grants (OCE-1260424 and OCE-1459546), and an NSF Doctoral Dissertation Improvement Grant (IOS-1501651). The authors would also like to thank the Marine Aquarium Societies of North America's Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research for offsetting the open access publishing costs of this article. More info at tiny.cc/MASNAPubFund. All work was approved by the Belize Fisheries Department and the Boston University IACUC (protocol # 10-036). (Trustees of Boston University; Warren McLeod Summer Research Scholarship - Boston University Marine Department; OCE-1260424 - NSF; OCE-1459546 - NSF; IOS-1501651 - NSF Doctoral Dissertation Improvement Grant; IDC account; Marine Aquarium Societies of North America's Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research)Published versio

A Technique to Derive Improved Proper Motions for Kepler Objects of Interest

We outline an approach yielding proper motions with higher precision than exists in present catalogs for a sample of stars in the Kepler field. To increase proper motion precision we combine first moment centroids of Kepler pixel data from a single Season with existing catalog positions and proper motions. We use this astrometry to produce improved reduced proper motion diagrams, analogous to a Hertzsprung-Russell diagram, for stars identified as Kepler Objects of Interest. The more precise the relative proper motions, the better the discrimination between stellar luminosity classes. With UCAC4 and PPMXL epoch 2000 positions (and proper motions from those catalogs as quasi-bayesian priors) astrometry for a single test Channel (21) and Season (0) spanning two years yields proper motions with an average per-coordinate proper motion error of 1.0 millisecond of arc per year, over a factor of three better than existing catalogs. We apply a mapping between a reduced proper motion diagram and an HR diagram, both constructed using HST parallaxes and proper motions, to estimate Kepler Object of Interest K-band absolute magnitudes. The techniques discussed apply to any future small-field astrometry as well as the rest of the Kepler field.Comment: Accepted to The Astronomical Journal 15 August 201